Iodomethane difluoride

Anhydrous HgFg added at room temp, to soln. of xenon difluoride in methyl iodide, allowed to stand 20 min., phenylacetylene added to the resulting soln. of iodomethane difluoride, and allowed to stand 2.5 hrs. at room temp. (Z)-l-fluoro-2-iodo-l-phenylethylene. Y 75%. F. e. s. M. Zupan, Synthesis 1976, 473. 

As noted above, it is not easy to purify unsubstituted hydrazones. Therefore, reactions of hydrazone derivatives with iodine monofluoride have also been studied (Table 1). A-Methyl-and iV,iV-dimcthylhydrazones react more slowly than unsubstituted hydrazones with iodine monofluoride higher tempteratures are often required for their conversion into ge/w-difluorides (Table 1). The reason for this behavior is that elimination of iodomethane from the intermediates is less favorable (see Scheme 1, R = Me). The use of pure derivatives increases the yield in cases sensitive to hydrolysis (cf. entries 25 and 26). 2,4-Dinitrophenylhydrazones only react with iodine monofluoride at temperatures above O C. The yields are generally lower than in the case of unsubslituted hydrazones, and 2,4-dinitrophenylhydrazones formed from aldehydes are unreaetive. 

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